Psoriasis is a T-cell mediated autoimmune disease characterized by increased keratinocyte proliferation. In psoriasis, chemokines are secreted by a wide variety of cells (e.g. keratinocytes, dendritic cells, monocytes), which migrate immune cells (Th17 cells, Th1 cells, neutrophils, etc.) involved in the pathogenesis. Bath-psoralen plus ultraviolet A (PUVA) treatment is an established phototherapy for psoriasis, but its effects on chemokine levels remain unknown. We measured the levels of 22 serum chemokines by using a flow cytometry bead-based immunoassay in 20 psoriasis patients first treated with bath-PUVA therapy between 2007 and 2011 in our hospital. We analyzed the associations among chemokines with disease severity (psoriasis area and severity index, PASI) before and after the therapy to identify the chemokines involved in the pathogenesis of psoriasis and investigate the mechanisms of action of bath-PUVA therapy. The median PASI score before bath-PUVA therapy was 23.8 (range 5.6–69.3). All patients showed a decrease in the PASI score following treatment (median score 2.0, range 0–9.1). Before bath-PUVA therapy, the PASI scores correlated with the serum levels of CCL17 (r = 0.581), CCL18 (r = 0.462), CCL19 (r = 0.477) and CXCL16 (r = 0.524). After bath-PUVA, the serum levels of CCL17, CCL22, CXCL1, and CXCL9 were significantly decreased. And heatmap clustering and network analysis based on Spearman correlations among chemokines showed distinctive pattern changes in the chemokine signature between before and after the therapy. We found 4 chemokines correlated with the disease severity of psoriasis. In addition, 4 chemokines decreased after bath-PUVA therapy was found to be secreted by keratinocytes from previous papers, so we partly revealed the mechanism that bath-PUVA therapy reduced the secretion of keratinocyte-derived chemokines which induce the migration of immune cells important for psoriasis pathogenesis.

ESDR082 - Bath-PUVA therapy ameliorates pathogenetic chemokines for psoriasis

50th Annual Meeting of the European Society for Dermatological Research. VIRTUAL MEETING